Stimulation of chlorophyll synthesis in cucumber cotyledons by benzyladenine

1973 ◽  
Vol 51 (5) ◽  
pp. 937-939 ◽  
Author(s):  
R. A. Fletcher ◽  
C. Teo ◽  
A. Ali
Keyword(s):  
Total Synthesis ◽  
Aminolevulinic Acid ◽  
Chlorophyll Biosynthesis ◽  
Chlorophyll Synthesis ◽  
Lag Phase ◽  
Cucumber Cotyledons ◽  
Ala Synthetase ◽  
Rate Limiting ◽  
Chlorophyll Formation ◽  
Stimulation Of

When exposed to light, etiolated cucumber cotyledons exhibited a lag phase in chlorophyll biosynthesis. Pretreatment of the cotyledons with benzyladenine (BA) eliminated the lag phase and stimulated chlorophyll formation. In BA-treated cotyledons, the incorporation of 14C-leucine into protein and the total synthesis of protein were higher than in the non-BA-treated controls. After BA treatment and exposure to light, the accumulation of δ-aminolevulinic acid in the cotyledons increased with time and was higher than in the controls, where a lag phase was apparent. These results support our hypothesis that BA affects chlorophyll formation by inducing the production of proteins including ALA-synthetase, the rate-limiting enzyme in chlorophyll biosynthesis.

Benzyladenine as a regulator of chlorophyll synthesis in cucumber cotyledons

1971 ◽  
Vol 49 (12) ◽  
pp. 2197-2201 ◽  
Author(s):  
R. A. Fletcher ◽  
Dianne McCullagh
Keyword(s):  
Aminolevulinic Acid ◽  
Chlorophyll Biosynthesis ◽  
Chlorophyll Synthesis ◽  
Lag Phase ◽  
Rna And Protein Synthesis ◽  
Chlorophyll Production ◽  
Cucumber Cotyledons ◽  
Ala Synthetase ◽  
Rate Limiting ◽  
Chlorophyll Formation

Pretreatment of etiolated cucumber cotyledons (4–10 days old) with benzyladenine (BA) increased the amount of chlorophyll produced in light. BA also eliminated the lag phase in chlorophyll formation, which in the water controls lasted for [Formula: see text]. Addition of δ-aminolevulinic acid (ALA) to the etiolated cotyledons resulted in the production of protochlorophyllide (PCHLD) in the dark. The BA-pretreated cotyledons did not make any PCHLD in the dark. The inhibitors of RNA and protein synthesis, actinomycin D, chloramphenicol, and cycloheximide (CH), inhibited BA's effect on chlorophyll production, with CH being the most effective. We propose that BA's effect on increased chlorophyll formation is mediated by inducing production of proteins including ALA synthetase, the rate-limiting enzyme in chlorophyll biosynthesis.

Induction of delta-aminolevulinic acid synthetase in muscle by exercise or thyroxine

1979 ◽  
Vol 236 (3) ◽  
pp. R180-R183 ◽  
Author(s):  
J. O. Holloszy ◽  
W. W. Winder
Keyword(s):  
Thyroid Hormones ◽  
Aminolevulinic Acid ◽  
Treadmill Running ◽  
Synthetase Activity ◽  
Mitochondrial Enzymes ◽  
Vigorous Exercise ◽  
Ala Synthetase ◽  
Rate Limiting ◽  
Rate Controlling Step ◽  
Mitochondrial Cytochromes

There is evidence that delta-aminolevulinic acid (ALA) synthetase is the rate-limiting enzyme in heme biosynthesis. Accumulation of the apoproteins of the mitochondrial cytochromes appears to be regulated by availability of heme. Exercise and thyrotoxicosis bring about increases in the cytochromes, and in other mitochondrial enzymes, in muscle. In this context, we have examined the effects of exercise and of thyroid hormones on ALA synthetase activity in skeletal muscle. Treadmill running and injection of thyroid hormones both resulted in significant increases in muscle ALA synthetase activity. A rise in ALA synthetase activity was evident within 17 h after a bout of vigorous exercise and 14 h after a single injection of thyroid hormones. The increase in ALA synthetase preceded the increase in cytochrome c, which was used as a mitochondrial marker. These results are compatible with the hypothesis that a relationship exists between heme synthesis and mitochondrial growth in which the rate-controlling step is ALA synthetase activity.

scholarly journals No effect of plant growth retarding compounds and growth stimulators on indolo-3-acetic acid oxidase activity in greening cucumber cotyledons

2015 ◽  
Vol 42 (3) ◽  
pp. 441-452 ◽  
Author(s):  
J. S. Knypl
Keyword(s):  
Oxidase Activity ◽  
Chlorophyll Synthesis ◽  
Lag Phase ◽  
Acid Oxidase ◽  
Iaa Oxidase ◽  
Crude Enzyme Extract ◽  
Chlorophyll Accumulation ◽  
Cucumber Cotyledons ◽  
Amo 1618 ◽  
Molecular Sieving

Cotyledons dissected from 5-day-old etiolated cucumber seedlings were incubated in solutions on AMO-1618, B-Nine, CCC and Phosfon D for 48 h in light. In some tests the retardants were applied in mixed solutions with GA<sub>3</sub> or BAP. IAA oxidase was extracted and purified by means of molecular sieving through a bed of Sephadex G-25. The retardants inhibited chlorophyll synthesis by 50 % or more, and had essentially no effect on IAA oxidase activity per cotyledon basis. GA<sub>3</sub> and BAP also had no effect on enzyme activity in spite of a fact that the compounds stimulated growth of the cotyledons. The crude enzyme extract from B-Nine treated cotyledons showed lower IAA oxidase activity in comparison with the water treated control, the effect being due to a longer lag-phase preceding the initiation of IAA oxidation. KNO<sub>3</sub> strikingly stimulated expansional growth of the cotyledons, the effect being correlated with the accelerated chlorophyll accumulation. KNO<sub>3</sub> had no effect on IAA oxidase activity per cotyledon and decreased it per gram fr wt. It is concluded that [1] the growth rate of cucumber cotyledons is not correlated with IAA oxidase activity, and ;[2] the growth retarding compounds do not affect IAA oxidase system is this tissue.

scholarly journals Porphyrin Synthesis by Cultured Lymphocytes

Blood ◽  
1972 ◽  
Vol 39 (4) ◽  
pp. 568-574 ◽  
Author(s):  
Alan S. Josephson ◽  
Richard D. Levere ◽  
Ivan Lowenthal ◽  
Fred Swerdlow ◽  
Mark Ginsberg
Keyword(s):  
Culture Medium ◽  
Aminolevulinic Acid ◽  
Sex Steroid ◽  
Heme Synthesis ◽  
Peripheral Lymphocytes ◽  
Porphyrin Synthesis ◽  
Ala Synthetase ◽  
Rate Limiting ◽  
Steroid Metabolite ◽  
Cells Cultured

Abstract Peripheral lymphocytes were cultured in the presence and absence of phytohemagglutinin (PHA). Porphyrin synthesis was visually estimated by fluorescence and quantitated by fluorometry. No visual fluorescence was noted in cells cultured with or without PHA. Addition of δ-aminolevulinic acid (ALA) to cultures of either transformed or nontransformed lymphocytes resulted in fluorescence, indicating porphyrin synthesis. Certain sex steroid metabolites stimulate porphyrin synthesis by induction of the rate-limiting enzyme ALA synthetase. Erythropoietin also increases the rate of heme synthesis. Phytohemagglutinin-transformed and nontransformed cells were cultured with the addition of either 11-keto pregnanolone or erythropoietin, and neither agent induced porphyrin synthesis. Only when ALA was added to the culture medium was the measured fluorescence statistically greater than in control cultures. These studies indicate that the enzymes of porphyrin synthesis distal to ALA synthetase, the rate-limiting enzyme, are present in all cultured lymphocytes. The rate-limiting enzyme is not induced by PHA transformation, even in the presence of a 5-β-H steroid metabolite or erythropoietin.

Sign in / Sign up

Export Citation Format

Share Document